Molecular basis for the reverse reaction of African human trypanosomes glycerol kinase
Molecular basis for the reverse reaction of African human trypanosomes glycerol kinase
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DOI：
10.1111/mmi.12831
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发表时间：
2014-12-01
影响因子：
3.6
通讯作者：
Harada, Shigeharu
中科院分区：
文献类型：
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作者：
Balogun, Emmanuel Oluwadare;Inaoka, Daniel Ken;Harada, Shigeharu
非洲人锥虫的甘油激酶(GK)在他们的糖体中被分割。与宿主GK不同，宿主GK在生理条件下只催化正向反应(依赖于ATP的甘油磷酸化)，锥虫GK还可以催化反向反应。事实上，由于这种独特的反向催化作用，GK对寄生虫在人体内的生存可能是必不可少的，因此是一个有希望的药物靶点。其反向催化的机制尚不清楚；因此，尚不清楚这种能力是否纯粹是由于其在细胞器中的定位，或者是否基于结构的催化差异也起到了作用。为了研究这种信息的缺乏，该蛋白质的X射线晶体结构被测定到1.90埃分辨率，以其未连接的形式，并在三个天然配体的络合物中。这些数据结合结构导向突变的结果表明，锥虫GK可能是一种短暂的自磷酸化苏氨酸激酶，其催化位点由非保守残基形成。我们的结果提供了该酶的一系列结构特征，并为反向催化机理提供了意想不到的见解。总之，它们为锥虫GK特异性抑制剂的开发提供了一个令人鼓舞的分子框架，这可能导致设计出新的、更安全的杀锥虫药物(S)。
The glycerol kinase (GK) of African human trypanosomes is compartmentalized in their glycosomes. Unlike the host GK, which under physiological conditions catalyzes only the forward reaction (ATP-dependent glycerol phosphorylation), trypanosome GK can additionally catalyze the reverse reaction. In fact, owing to this unique reverse catalysis, GK is potentially essential for the parasites survival in the human host, hence a promising drug target. The mechanism of its reverse catalysis was unknown; therefore, it was not clear if this ability was purely due to its localization in the organelles or whether structure-based catalytic differences also contribute. To investigate this lack of information, the X-ray crystal structure of this protein was determined up to 1.90 angstrom resolution, in its unligated form and in complex with three natural ligands. These data, in conjunction with results from structure-guided mutagenesis suggests that the trypanosome GK is possibly a transiently autophosphorylating threonine kinase, with the catalytic site formed by non-conserved residues. Our results provide a series of structural peculiarities of this enzyme, and gives unexpected insight into the reverse catalysis mechanism. Together, they provide an encouraging molecular framework for the development of trypanosome GK-specific inhibitors, which may lead to the design of new and safer trypanocidal drug(s).